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Mechanism of SCN− ions affecting the adsorption of Au(CN)2- ions on anion exchange resin
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DOI：10.3389/fchem.2026.1908266.png)
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Abstract
En 中文
The cyanide leaching process for gold ore is a mainstream gold extraction method due to its high gold leaching efficiency and strong ore adaptability. The resin-in-pulp process is an important cyanidation-based gold recovery technique; which employs weakly basic anion exchange resins with high selectivity and large adsorption capacity as adsorbents; offering the significant advantage of high adsorption efficiency. However; in practical production; repeated resin recycling accumulates SCN− in pulp from residual thiocyanate desorption released during each reuse; significantly reducing Au(CN)2- adsorption efficiency. To address this issue; this study focuses on the macroporous weakly basic anion exchange resin D301 used in a gold mine in Chifeng; Inner Mongolia; China. Through single-factor tests and comparative experiments; the influence of SCN− ions on the adsorption of Au(CN)2- by the resin was investigated. Experimental results indicate that under conditions where SCN− ions are present; increasing the experimental temperature or initial solution pH reduces the adsorption efficiency of Au(CN)2-; whereas increasing the resin dosage effectively enhances adsorption. Microscopic characterization further elucidates the mechanism by which SCN− affects the adsorption process. SEM-EDS analysis reveals that SCN− diminishes the resin’s adsorption capacity for Au(CN)2-. FTIR spectra show the simultaneous presence of characteristic peaks for Au(CN)2- (C≡N) and SCN− (S–C≡N) on the resin surface; confirming their coexistence. XPS results further verify the existence of characteristic peaks for Au and S elements; indicating that while gold is adsorbed in the form of Au(CN)2-; the resin also adsorbs SCN− from the solution. In summary; SCN− and Au(CN)2- exhibit a competitive adsorption mechanism on D301 resin; which is the primary cause of the decreased adsorption efficiency of Au(CN)2-. It is recommended that when the concentration of SCN− in the pulp accumulates to a high level during the resin-in-pulp gold extraction process; it should be removed by oxidation; thereby enabling efficient adsorption of Au(CN)2- by the resin. This study provides both theoretical and experimental foundations for addressing SCN− interference and optimizing resin-based gold extraction processes.
Keywords:
adsorption mechanism
resin
gold cyanide complex ion
resin-in-pulp process
thiocyanate ion
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